The blending of aromatic poly(arylethersulfone) (PAES) polymers, such as notably polyphenylsulfone (PPSU), polyethersulfone (PESU), bisphenol A polysulfone (PSU) and high temperature sulfone (HTS) polymers, for example the commercially available EpiSpire® HTS high temperature sulfone polymer and Supradel® HTS high temperature sulfone polymer, with poly(aryletherketone) PAEK polymers including in particular poly(etheretherketone) (PEEK), poly(etherketone) (PEK) and poly(etherketoneketone) (PEKK) polymers have known a growing interest because of the exceptional properties that can be achieved.
Certain PEEK/PPSU blends offer a good and unique combination of properties and have been valued for years in specific end uses in particular in plumbing end-use applications such as fittings, tubes, manifolds etc. However, these blends are rather expensive due to the high cost of both the PEEK and the PPSU components.
PAEK/PAES polymer blends are also known for their exceptional overall properties and have been used in a variety of applications such as notably medical device and instrument applications such as sterilizable surgical instruments and instrument handles, sterilizable cases and trays, and related components, aircraft light structural components and mobile electronic device components but certain PAEK/PAES polymer blends are characterized by some drawbacks.
One of the main issues in blending aromatic poly(arylethersulfone) polymers with poly(aryletherketone) polymers is the limited compatibility between the two polymers. Especially, the PEEK/PESU and PEEK/high temperature sulfone (HTS) polymer blends are suffering from this limited compatibility exhibiting consequently poor impact resistance, and poor melt processability manifested as severe die swell during melt compounding operations used to prepare these blends. The die swell results in difficulty producing these blends on large industrial scale because the process is unstable due to the inability to maintain a uniform extrudate strand thickness during the process. For example, it has been found that blends of PEEK and PESU when melt compounded exhibit strong die swell because of the above mentioned limited compatibility between the two polymers.
Thus, there remains a need to improve the compatibility between poly(aryletherketone) polymers and aromatic poly(arylethersulfone) polymers other than PPSU, thereby affording compositions having enhanced toughness and impact resistance, while maintaining all the other exceptional properties and being cost attractive over the existing prior art PAEK/PAES blends.